Guard intervals are used to ensure that distinct transmissions do not interfere with one another.
These transmissions may belong to different users (as in Time Division Multiple Acces) or to the same user (as in Orthogonal Frequency-Division Multiplexing).
In COFDM, the beginning of each symbol is preceded by a guard interval. As long as the echoes fall within this interval, they will not affect the receiver's ability to safely decode the actual data, as data is only interpreted outside the guard interval.
What is Guard Interval in DVB-T and DVB-T2 systems?
What is the use of guard interval in radio communications? What are the values of guard interval available in DVB-T and DVB-T2?
What are the values of guard interval available in DVB-T?
In DVB-T you can choose between four GI periods:
1/32, 1/16, 1/8, 1/4
What are the values of guard interval available in DVB-T2?
In DVB-T2 you can choose between seven GI periods:
1/128, 1/32, 1/16, 19/256, 1/8, 19/128, 1/4
What are the differences between GI values?
1/32 period gives the lowest protection (symbol duration is short) and the highest bitrate. 1/4 results in the best protection (receiver waits longer for all delayed symbols) but it has the lowest data rate.
In order to know the duration of each GI please use DVB-T Calculator.
source: satbroadcasts.com / EBU
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